The present invention relates to lighting fixtures which employ reflective holographic optical elements to control and direct the radiation pattern of an artificial and incoherent light source. Related inventions are described in my prior U.S. Pat. No. 4,536,833 and in my copending application Ser. Nos. 897,295, 897,292, 897,296.
Known lighting fixtures, whether for interior architecture, road lighting, automobile headlights or theatrical spotlights employ enamelled, polished metal, or vacuum metallized reflectors to direct radiation from a light source in a given photometric pattern. Ray tracing techniques are used to determine the proper contours of the reflector to achieve maximum efficiency in these fixtures, but the overall efficiency is nonetheless limited because ray tracing techniques rely on the erroneous assumption that incandescent filaments are actually point sources. Specifically, any given point on the reflector can provide the correct angle of reflection only for radiation of the correct angle of incidence. Incandescent filaments provide radiation at a variety of angles, however, and radiation reaching the reflector from other than the correct angle is reflected at some different, non-optimum angle leading to a loss of light intensity from the targeted task area.